Motion picture photographic films used in producing a release print (the film projected in movie theaters) include camera origination film, intermediate film, and the release print film. Current practice for most color motion picture production involves the use of at least four photographic steps. The first step is the recording of the scene onto a camera negative photographic film. While the original negative (typically after editing) may be printed directly onto a negative working print film in a second step to produce a direct release print, most motion picture productions use an additional two intermediate steps. Typically, the original camera negative film is printed onto a negative working intermediate film, such as Eastman Color Intermediate Film, yielding a master positive. The master positive is subsequently printed again onto an intermediate film providing a duplicate negative. Finally, the duplicate negative is printed onto a print film forming the release print. In practice, several duplicate negative copies are produced from the master positive, and each of the duplicate negatives may then be used to make hundreds of print film copies. This multistep process helps save the integrity of the valuable original camera negative film in preparing multiple release prints. In certain situations, usually involving special effects, intermediate film may be used an additional two or more times in preparing the final duplicate negatives to be used in printing the release prints. In this case, the first duplicate negative is used to print onto intermediate film to produce a second master positive, which is in turn used to produce a second duplicate negative. The second duplicate negative may be then used for printing the release prints.
The photographic industry has long recognized the need to provide photographic elements with some form of antihalation protection. Halation has been a persistent problem with photographic films comprising one or more photosensitive silver halide emulsion layers coated on a transparent support. The emulsion layer diffusely transmits light, which then reflects back into the emulsion layer from the support surface. The silver halide emulsion is thereby reexposed at locations different from the original light path through the emulsion, resulting in "halos" on the film surrounding images of bright objects.
One method frequently employed for antihalation protection in photographic films comprises providing a dyed or pigmented layer behind a clear support as an antihalation backing layer, wherein the backing layer is designed to be removed during processing of the film. Typical examples of such antihalation backing layers comprise a light absorbing dye or pigment (such as carbon black) dispersed in an alkali-soluble polymeric binder (such as cellulose acetate hexahydrophthalate) that renders the layer removable by soaking in an alkaline photographic processing solution, scrubbing the backside layer, and rinsing with water. Such carbon containing "rem-jet" backing layers have been commonly used for antihalation protection in motion picture origination, intermediate, and print release films. The carbon particles additionally provide antistatic protection prior to being removed, helping to avoid fogging caused by sparks during film transport. Photographic films utilizing a carbon black-containing layer are described, e.g., in U.S. Pat. Nos. 2,271,234, 2,327,828, 2,976,168, 3,753,765, 3,881,932, 4,301,239, 4,914,011, and 4,990,434.
While such carbon black containing backing layers provide effective antihalation and antistatic protection for photographic films prior to processing, their use requires special additional processing steps for their subsequent removal, and incomplete removal of the carbon particles can cause image defects in the resulting print film. Additionally, it has been found to be desirable to provide "process surviving" antistatic protection for motion picture print films in order to prevent static build-up even after imagewise exposure and processing, as such print films are subject to rapid transport through projection apparatus where static charges can attract dust particles which may detrimentally impact a projected image. Accordingly, alternatives for carbon-containing, process-removable, antihalation/antistatic backing layers have been proposed for motion picture films. One such alternative is to use antihalation undercoat layers containing filter dyes coated between the support and the emulsion layers wherein the filter dyes are solubilized and removed and/or decolorized during processing of the film, and a separate process-surviving antistatic backing layer, such as described in U.S. Pat. Nos. 5,679,505 and 5,723,272. Dyes may be selected and used in combinations to provide antihalation protection throughout the visible spectrum. Process-surviving antistatic layers typically include, e.g., ionic polymers, electronic conducting non-ionic polymers, and metal halides or metal oxides in polymeric binders. Conductive fine particles of crystalline metal oxides dispersed with a polymeric binder have been found to be especially desirable for preparing optically transparent, humidity insensitive, antistatic layers for various imaging applications. The use of such antihalation undercoat and process-surviving antistatic protection layers in recent commercial motion picture print release films has resulted in improved (i.e., decreased) dirt levels observed upon projection of motion picture images.
A motion imaging film having on one side of a support material, in order, a process surviving, electrically conductive subbing layer, a photographic emulsion, and a protective overcoat; and on the opposite side a carbon black-containing backing layer, and optionally, a lubricant layer is described in U.S. Pat. No. 5,747,232. Although the '232 patent discloses the use of motion imaging films having a process surviving subbing conductive layer, the retained need for the use of carbon black-containing layers is undesirable from the standpoint of film cleanliness. In addition, after processing the lubricant that is normally applied over the carbon black-containing layer is also removed and, therefore, the processed film has a high coefficient of friction on the backside of the film which is undesirable for good transport and film durability during repeated cycles in a high speed printer.
The use of antihalation undercoat layers and interlayers in place of carbon-containing backing layers has also been suggested for camera origination and intermediate films, such as disclosed, e.g., in EP 0582 000. Such suggestions, however, have not included reference to the need for process-surviving antistatic protection for such films, as these films are typically not used in theaters for projection purposes. EP 0 582 000 itself specifically states use of an antistatic layer comprising polystyrene sulfonic acid sodium salt is preferred, which material would not provide substantially process-surviving antistatic protection, as without a protective topcoat the antistatic performance of these electroconductive polymers may be greatly diminished after processing.
While the use of antihalation undercoat layers and process-surviving antistatic backcoat layers in recent commercial motion picture print release films has resulted in improved (i.e., decreased) dirt levels observed upon projection of motion picture images, it would be desirable to further decrease dirt and other image defect levels observed during projection of motion picture films.